1. Field of the Invention
The present disclosure relates to fluid conditioning systems. More particularly, the present disclosure relates to systems for conditioning multiphase fluids, such as mixing and/or splitting such fluids in connection with a subsea and/or topside multiphase pumping system.
2. Background of the Technology
In fluid processing systems, such as multiphase pumping stations, a multiphase pump can be combined with an upstream multiphase mixer and downstream flow splitter. The multiphase mixer utilizes a large volume tank and it is advantageous to design the mixer for long-term installation on the sea floor. Because the multiphase mixer is often intended to be deployed for long periods of time, up to the lifetime of the field, it should be designed to deal with a relatively wide operating envelope in terms of both flow rate and gas volume fraction (GVF). However, the larger the operating envelope, the greater the compromise in mixer performance. For example, the mixer may be designed larger than ordinary in order to handle hydrodynamic slugging, while at the same time the annulus clearance may be designed smaller in order to push the operating envelope up toward higher GVF levels.
Another challenge to multiphase mixers that are designed for long-term deployment is the accumulation of sand and other solid debris. Recent findings show that in some fields, accumulations of sand and solid debris are possible within the volume of multiphase subsea upstream mixers. Additionally, because the differential pressure across the liquid flow path in the mixer and splitter is substantially less than the pressure differences across the pump, it is easier to block a mixer compared to a pump, assuming the same size of clearance.
Yet another challenge in multiphase pumping stations is starting up a dead field. The pumping station might be designed such that the flow splitter is self-draining into the bypass header, which in turn is self draining into the flow line. There is hence a risk, when starting up a dead field where there are no free flowing wells. In such cases, the pump station can be quickly emptied of liquid if there is some amount of gas in the flow line upstream of the pump station. No or limited amounts of liquid inside the station will reduce the available draw down and hence limit the ability to start a dead field.